Summary
Using PR_URL_COMPNAME to bind to an item in WebDAV from CDO/MAPI involves understanding the encoding rules for the Exchange version where the item is homed. These rules are different and incompatiable between Exchange 2000, Exchange 2000...

The Exchange Team has a great new post on the future of Public Folders in Exchange 12 and understanding how they are implemented. Be sure to read this post if you are thinking about moving to Exchange 12 and/or Outlook 2007, this article will provide...

...Don't know if many people try to use this anymore but it is worth noting...
SYMPTOM
Receive MAPI_E_FAILONEPROVIDER when attempting to log on anonymously to Exchange 200x using CDO 1.21.
...OR...
After anonymous log on to Exchange...